Peptides showing antipathogenic and especially antimicrobial activity are already known in the art. Specifically of importance are the so-called lytic peptides, some of which are known to be active against a broad range of organisms while others produce little or no effect. There are many examples of lytic peptides from animal, plant, insect and microbial sources including the mammalian defensins, cecropins, thionins, mellitins, insect defensins, magainins, attacins, dipterins, sapcoins, caerulins, xenopsins, or hybrids thereof. The amino acid sequence of several lyric peptides with antimicrobial activity are disclosed in WO 89/04371. Lehrer et al. (1986) disclose six antimicrobial peptides (AMPs) from rabbit granulocytes that are structurally homologous to human neutrophil defensins. Three of the rabbit AMPs (NP-1, NP-2 and NP-3a) are disclosed to be effective against Candida albicans.
Another class of peptides with antipathogenic activity is represented by hydrolytic enzymes, such as chitinase and .beta.-1,3-glucanase, which are known to inhibit fungal growth (Schlumbaum et al., 1986; Mauch et al., 1988).
The present invention provides a further class of peptides which were found to be active against a broad range of pathogens affecting plants. This class of peptides embraces known as well as novel representatives. These peptides are especially suited for use in an antipathogenic composition for controlling plant pathogens.
It is, therefore, one of the objects of the present invention to provide an antipathogenic composition for controlling plant pathogens comprising together with a suitable carrier customarily used in agricultural peptide formulations an antipathogenically effective amount of a peptide according to the present invention.
It is another object of the invention to provide a method of protecting plants from the attack of plant pathogens, preferably from the attack of pathogenic bacteria and/or fungi, and most preferably from the attack of pathogenic bacteria, which comprises applying an antipathogenically effective amount of a peptide according to the invention or an anti-pathogenic composition containing said peptide to the plant or to the plant pathogen's habitat.
It is another object of the invention to provide novel antipathogenic peptides that can be used as active ingredients in a composition according to the invention.
It is a further object of the invention to provide methods of preparing an antipathogenic peptide according to the invention and a composition containing said peptide.
It is a further object of the present invention to provide transgenic plants with anti-pathogenic effective activity based on the expression of one or more inventive peptides in the plant cells.
It is another object of the present invention to provide transgenic plants that contain DNA sequences coding for the inventive peptides.